The Desmoplastic Reaction Surrounding Hepatic Colorectal Adenocarcinoma Metastases Aids Tumor Growth and Survival via αv Integrin Ligation

Purpose: The treatment of metastatic colorectal carcinoma represents a major clinical challenge. We investigated the hypothesis that the desmoplastic reaction within the liver elicited by metastatic adenocarcinoma, characterized by Collagen I deposition and altered Collagen IV distribution, promotes the growth and survival of hepatic colorectal carcinoma metastases. Experimental Design: Partial hepatectomy specimens for metastatic colorectaladenocarcinorna were examined immunohistochemically for differential integrin expression. Human colorectal adenocarcinoma Cell lines HT-29, KM12SM, and KM12c were grown on wild-type collagen I or IV, or cleavage-resistant r/rcollagen I, and assessed for their growth, survival, and resistance to 5-fluorouracil. The effect of alpha(v)beta(3) and alpha(v)beta(5) integrin blockade by neutralizing antibodies was examined. Results: Collagen 1, in contrast to collagen IV, significantly enhanced the growth, survival, and chemoresistance of colorectal carcinoma cells. Blockade of the alpha(v)beta(3) and alpha(v)beta(5) integrins significantly reduced colorectal carcinoma cell proliferation on collagen, especially in the cell line with the most metastatic potential. These in vitro findings correlated with the pattern of integrin expression identified within resected hepatic colorectal carcinoma metastases. Using matrix metalloproteinase-resistant r/r collagen I as a dominant negative ligand for alpha(v) integrins, we showed a key role for this integrin-ligand interaction in mediating the survival and proliferation of colorectal carcinoma cells. Conclusions: Desmoplasia has an important role in the development of hepatic colorectal carcinoma metastasis. The interaction between integrin and collagen I is identified as a potential therapeutic target.